1. Field of Invention
The present invention relates to an optical modulation device retainer for retaining an optical modulation device that modulates color light beams depending on image information, an optical device, and a projector.
2. Description of Related Art
Currently a projector exist that are of a type including a plurality of optical modulation devices for modulating various color light beams on a color light beam basis in accordance with image information, a color synthesizing optical device for forming optical images through synthesis of the modulated color light beams, and a projection lens for enlarging and projecting thus formed optical images.
In the projector of such a type, a dichroic mirror exemplified for a color separation optical system separates a light flux coming from a light source into color light beams of three colors. Three optical modulation devices each structured by a liquid crystal panel, or the like, can perform modulation on a color light beam basis in accordance with image information. A cross dichroic prism exemplified for a color synthesizing optical device forms optical images by synthesizing the modulated color light beams. The projection lens enlarges and projects the resulting optical images.
In such a projector, the optical modulation devices all have to be located at the back focus position of the projection lens. Moreover, to obtain clearer images, the projector needs to prevent pixel displacement among the optical modulation devices, and distance change from the projection lens.
In view thereof, as disclosed in for example, JP-A-2000-221588, at the time of projector manufacturing, it is known that focus adjustment for correctly placing the optical modulation devices at the back focus position of the projection lens, and alignment adjustment for pixel matching among the optical modulation devices are applied with high accuracy. Then, the optical device is directly fixed to a light flux incident end face of the color synthesizing optical device after the optical modulation devices are adjusted in position.
This optical device is so structured that a liquid crystal panel is accommodated in a retaining frame having a hole formed at its four corners, and the holes are each inserted with a pin whose surrounding is coated with adhesives. Then, the end face of the pin can be securely affixed together with the light flux incident end face of the cross dichroic prism, and the side face of the pin with the corresponding hole of the retaining frame. At the rear stage of the liquid crystal panel, a polarization plate is placed as an optical conversion element. This polarization plate is directly attached to the light flux incident end face of the cross dichroic prism.